Today in Morbidity and Mortality Weekly Report, researchers published findings showing adults who received an updated 2023-24 COVID-19 vaccine were 54% less likely to have symptomatic infection than those who didn’t, and the vaccine was found to protect against JN.1 and other circulating variants.

This is one of the first studies to update 2023-24 COVID vaccine effectiveness (VE) data. The monovalent (single-strain) booster vaccine derived from XBB.1.5 was approved for use in all Americans 6 months and older on September 12, 2023, but uptake has been low. Moreover, the XBB strains of the virus, which the vaccine was based on, are no longer the dominant strains in the United States, having been replaced by JN.1 in December 2023.